Hydraulic fracturing is a technology that contributes to improvements in oil and gas production. Hydraulic fracturing is used to create additional passageways in the oil, gas, and/or coalbed reservoir that can, by way of example, facilitate the flow of oil and/or gas to a producing well. Unconventional reservoirs such as shale gas reservoirs, coalbed methane reservoirs, and “tight gas” reservoirs, such as those whose gas-containing matrix have restricted porosity and permeability that impede the flow of oil or gas through the reservoir, are commonly fractured by injecting a fluid containing sand or other “proppant” and other ingredients under sufficient pressure to create fractures in the rock through which the desired product can more easily flow.
In hydraulic fracturing, the optimum spacing is a function of fluid flow and stress interference. The current trend in the industry is to place wells in a uniform manner and also place the fractures in an equally spaced distribution in the same time along the well path. The net pressure created as a result of introducing the first fracture will affect the initiation of the second and subsequent fractures, which sometimes leads to orientation of the fracture and a tortuositious path fracture. Therefore, some fracture stages are not successful in terms of accommodating proppant and in terms of production.
Additionally, it can be appreciated that shale possesses an ultra-low matrix permeability, which consequently requires the creation of hydraulic fracturing to maximize the contact area with the reservoir. The key to successful fracturing treatment in shale formation is the identification of the “sweet spots”. Productive shale consists of higher and easier to fracture portions, but also may include, for example, quartz, feldspar or carbonate and clays, in addition to organic matter (Kerogen). Thus, mapping the best zones to fracture is a challenging process.